In various processes requiring filtration of a fluid stream, filter tubes are generally employed either alone or disposed about a permanent support core which is an integral part of the filter assembly. Core supports are normally employed where the pressure drop across the filter tube when in service is expected to exceed the strength of the filter tube itself. Such filter tubes and their supports are normally placed within an external filter housing. In general, the filter tubes are made to rather standard sizes and then are disposed over an internal porous support core. Material to be filtered is generally introduced externally of the tube in the housing and clarified gas or liquid removed from the internal portion of the support core. Typically, the support core is an integral part of the cartridge and is disposed of when the replacement of the filter tube is required.
Support cores presently employed are generally fabricated from a rigid open mesh material to provide porosity, such as an expanded or perforated metal. For example, a sintered porous metal cylinder is often used as a support at very high pressure differentials, while the support core may also be comprised of screen material and the like. The support cores thus employed are unitary integral cores, the body of the core generally being formed in a single operation of generally inexpensive material with the core thrown away with the filter tube with which it is used. In addition, the porosity of the support core must be carefully selected so as to provide for the proper support, while minimizing flow resistance of the fluid stream through the support core. Accordingly, there exists a need and advantage for a support core which is easily fabricated from inexpensive materials and which offers porosity of desired characteristics, and yet which may be easily fabricated to a desired length to accommodate various filter tube lengths and wherein the filter tube only may be removed and discarded during service without the necessary removal from service or discarding of the support core.